Process of purifying bauxite



EEG-AIR, EV

an, r antenna, enenern,

PEUCEBS 0F PURIEFYING- BA'UXITE.

rename,

Ito Drawing.

To all whom it may concern:

Be it known that I, EDGAR Evnnnan'r, a citizen of the United States, residin at Atlanta, in the county of Fulton and tate of Georgia, have invented certain new and useful Improvements in Processes of Funfying Bauxite; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My present invention relates to the separation of clay or clay-like substances from low grade bauxite, in order to purify the.

latter sufi'iciently sq that it may be used in the industries, and so that it will pay for shipment for moderate distances. In certain localities there are considerable deposits of a low 'rade bauxite ore which contains mixed with the bauxite varying proportions of clay, which render the bauxite of low grade so that it will not fetch a sufficient price to warrant shipping the same for any considerable distances, and furthermore in many instances, this bauxite cannot be used asa source'of aluminum compoundson account of its high content of clay (which is a silicate) and the object of the present invention is to separate the two ingredients of such low grade ores sufficientl to produce a high grade or moderately high grade bauxite. T have discovered that if the bauxite is ground up and either simultaneously or subsequently treated with an appropriate solution, it is possible to float off thebulk of the clay and clay-like substances leaving the bauxite in a purified condition, in which it is usable for many purposes for wliich the original low grade ore is not suit ab e.

The bauxite is reduced to grains, which quickly settle in the water and deflocculating media, without so sliming the bauxite as to render it liable to suspension with the clay.

As the solution in which to float ofl the clay, I find that various alkalis or alkaline earths can be used to advantage, the clay remaining in suspension in such materials readily, while the bauxite separates out from the solution almost immediately.

Accordingly, the process of the present invention is preferably carried out as follows:

The ore is delivered preferably continuously to a wet grinding mill and a solution of an alkali, preferably caustic soda, is also Specification of Letters Patent.

va pliance filed February a, wee. semi n errata Patented Nov, 15, tacit,

delivered preferably continuously to the same mill. The ore is ground or crushed in the presence of the alkali solution to pass a screen of about 20 meshes to the linear inch. The liquid slurry flowing away from the mill then passes to an elutriation tank or trough, the water with the suspended clay 1s continuously floated off at the top while the ore 1s continuously removed from the bottom by means of a suitable elevating or conveying device. The flow is proportioned to secure the most eflicient separation and this will depend to a considerable extent on 7 the cost of caustic alkali at the place where the operatlon is to be conducted (namely, at the quarr or pit where the ore is taken out), the re ative proportions of clay and bauxite 1n the ore, value of bauxite and vanone other conditions. The strength of the caustic alkali also can be varied more or less, but for ordinary purposes, I find that a 0.02% solution gives satisfactory results and that an amount of this solution equal to about 800 gallons can conveniently be used, per ton of ore under treatment.

The bauxite recovered from the elutriation tank may be washed with water to remove and recover adhering soda, the liquor containing the clay and caustic soda solution can be run into settling ponds or tanks, and after the bulk of the clay has settled this liquor can be reused, being fortified if desired, by the addition of a further small quantity of alkali or the liquor can be limed to convert the carbonate back into caustic, then fortified with more caustic alkali and then reused. in such latter operation, the

amount of lime about chemically equivalent.

-water from the washing of the elutriated bauxite may be treated in a manner similar to the clay liquor for reuse. If desired the caustic soda solution can be thrown away after 'use. I s

I claim:

'1. A separating process, consisting in sub jecting claycontaminated bauxite ores to disintegration, and agitation, in a clay degrinding and agitation inan alkaline liquid, fiocculating liquid, until the clayey comuntil the clay particles are suspended and 10 ponents are suspended, and then separately, separately removing the suspended cla and removing the suspended clay and the granuthe granular bauxite; the grinding eing 5 lar bauxite; the disintegration being regu-i regulated to retain the bauxite in granular lated to retain bauxite in granular iorm. form.

2. A separating process consisting in subjeeting clay contaminated bauxite ores to EDGAR EVERHART. 

